1. Field of Invention
The present invention relates to a dimming control circuit capable of providing analog dimming, digital dimming and enable functions by one single pin. The circuit may be used in, e.g., an LED driver circuit.
2. Description of Related Art
As shown in FIG. 1, a typical prior art method for controlling LED brightness is to control the average current flowing through the LEDs (light emitting diodes) by the duty ratio of a digital dimming signal 101.
However, it is required to adjust the LED brightness in an analog manner in certain products. Under such circumstance, the analog input can only adjust the brightness, but can not provide any other function, nor can it provide any digital function. For example, if it is intended to adjust the LED brightness in the analog manner, and it is also desired to provide an enable function (e.g., to turn ON/OFF the LEDs), it is then required to provide both an analog input pin and a digital input pin EN, and corresponding circuits, to the driver circuit 10 shown in FIG. 1, which is obviously not cost-effective.
In view of the above, the present invention proposes a device and a method which is capable of generating analog and digital signals according to one input signal, to achieve a composite function of, e.g., dimming and ON/OFF control.